Process of recovering ammonia from gas.



PATENTED MAY 8, 1906 a. .1. mm. PROCESS OF ascnvsams AMMONIA PROM Gas;

APPLIGATEQEI FILED FEB. 10. 1905.

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No. 820,039. PATBNTED MAY 8, 1906. B. J. DUFF, PROCESS OF REGOVBEIIQGAMMONIA FROM GAS.

APPLICATION FILED 33.10. 1905.

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act descriptionthereof.

thermore, the gas as it comes from the prowasher.

' the percentage of ammonia which isrecovered UNITED STATES PATENTOFFICE.

EDWARD JAMES DUFF, OF LIVERPOOL, ENG-LAND. PROCESS OFRECOVERING AMMONIAFROM GAS Ho. esopae.

Patented May 8, 1906,

Application filed Iobruary 10 1905. Serial No. 245.116.

To all whom it may concern:

Be it known that I, EDWARD Janus DUFF, a resident of Live 001, in thecounty of Lan caster, England, ave invented a new and useful Improvementin Processes of Recovering Ammoniafrom Gas; and I do hereby deolare thefollowing to be a full, clear, and ex-' My invention relates to aprocess for cleaning and cooling artificial gases. and more especiallyfor the recovery of the by-products, such as ammonia, therefrom.

The object of my invention is to increase from the gas and also to povide for a saving in the amount of water used.

The invention is intended for the treatment of fuel-gases, andpar'ticularlyproducer-f 1gTasesthat is, those which are produced ombituminous coal by gasifying practically the whole of the carbonaceoussubstances contained in the coal. 7 ducer-gases have been scrubbed orwashed. and then subjected to the action of an ammoaria-absorbingliquor, such as sweet: solution of sulfate of ammonia conta' an excessof sulfuric acid, and then again sub'ected to a washing or cooling 0oration. e absorbing liquor removed one the gas the major portion oftheammonia-gas. A portion of ammonia, however, is absorbed b the waterdurin the first washing or scru hing step and 'aFso in the final washingand coolin step. Heretofore the ammonia absorbed by t e water in both'ofthese steps has been lost. Eurducer is very hot, so thatit evaporates aconsiderable amount of the water in the first Heretofore this vapor hasbeen lost and fresh water has had to be supplied by pumps or otherwiseto make up the deficiency. w r V The primary object of m invention is toincrease the yield of ammonia recovered from fuel-gases, andparticularlyfrom producer as. V g A further object of the invention is tocontinually return aportion of the water con-i densed from the gas inthe cooler to the washer for further use.

To these ends the invention consists, gen erally stated, in'subj ectingthe gases to wash- T ingand cooling operations as heretofore, and onjecting the water used for such washing and cooli operations to theaction of an ammonia-a sorbing" agent or liquor to recover Heretoforesuch prof:

from such water the ammonia which has been 7 absorbed thereby.

More particularly, the'invention consists in passing the gases insuccession through a sorubben thence through or over an absorb absorbedammonia to flow from the scrubber and mingle with the amm'onia-absorbinliquor (containin excess of sulfuric acid) oing circulated in t eammonia-absorbing tower.

In the accompanying drawin s, Figure 1 is an elevation of apparatussuite. is for ca ingroug y process. Fig. 2 is avi l P 3" in elevationand partly in vertical section, be-

ing taken at right angles to Fig. 1. Fig. 3 is a plan of the a aratus.Fig. 4 is a section on the lined 4, 1g. 3; and Fig. 5 is a section onthe line 5 5, Fig. 3.

In the apparatus illustrated the hot gas from the producer entersthrough a pipe 1 into the scrubber or washer 2. his maybe of any knownor desired type, that shown in the drawings being constructed as ahorizontal substantially rectangular box or flue partly filled withwater which is thrown up by an suitable mechanical means, such as the adles 4, into a spray or shower, entirely filling the chamber. may,however, be obtained b any other suitable means, such as bye grav ty-sray, from the top or roofof the chamber. T e purpose of this washer isto removei'rom the gas impuritiessuch asdust, soot, and tar-and at thesame time to reduce the temperature of thegas. Incidentally in thisprocess some of the ammonia is absorbed by the water, also some of thewater is evaporated by the-hotgas. My invention is particularly appliedtp the subsequent recovery of the ammonia ab sorbed by this water andthe return of the, condensed water to the scrubber. 5

The hot gas coming from the producer sees through the spray or shower ofwater 1n the scrubber and out at the op osite end thepee through a pipe5 to the use of the arnrnorna-absorbmg tower 6. When the gas This-sprayor shower of water 7 enters this tower, it still retain the bulk ofammonia gas originally contained therein.

To remove this, the tower6 is filled with perfoi rated bri "kwork 7 orother equivalentmeans; ;v

over whic a spray .or shower of ammoniaabsorbing liquor is kept incontinual circulation. This liquor ma be of any suitable na ture capableof absor ing the ammonia, such as a weak solution of sulfate of ammoniacontaining a slight excess of sulfuric acid. This liquor is continuallycirculated, being raised, by means of a pump 8 or other suitable means,from a receiving-tank 9 at the base of the tower to the top thereof. Thegas )asses upwardly through the perforated bric work and through thespra or shower of absorbing liquor flowipg over t e same, and saidliquor absorbs the ammonia in the usual and wellunderstood manner.

The purified gas escapes at the top of the tower and is conveyed by thepipe 10 to suitable gas-cooling apparatus, such as the tower 11, whichmay be of an suitable construction that shown bein fi led withperforated brickwork 12 or the he and over which is continuouslycirculated a stream or shower of cold water for the purpose of coolingand further washing the as. This water is kept in continuous circuation, being returned from the collecting-chamber 13 at thebase of thetower to the top thereof by means of a pump 14 or other suitable means.The shower falls downwardly throu h the tower, while the gas ssesupwardly t erethrough. The gas is still uite warm, so that the waterbecomes heated, and hence before being returned to the top of the toweris passed through any suitable cooling a paratus, which is diaammatically indicate at 15.

The gas a er leaving the absorbin -tower 6 still contains traces ofammonia, an this is partly or mostly absorbed by the cooling-water inthe tower 11. To recover the ammonia from this water, as ammoniaabsorbed by the water in the scrubr 2, I subject both of said waters tothe action of a suitable absorbing a ent, this preferably being theliquor circuTating through the tower 6. This can be convementlyaccomplished by returnin the excess of water from the receiving-tani 13to the scrubber '2as, for instance, through the pipe 16-and returningthe excess of water from the washer 2 to the receiving tank 9 through asuitable pipe 17. Before passing into the tank 9 the water passes throuh a settling-reservoir 18, in which the tar ust, soot, and otherimpurities are to a large extent removed from the water.

The apparatus is so arranged that the flow of water from thereceiving-tank 13 at the base of the coolingtower to the tank 9 at thebase of the ammonia-'absolbin tower is entirely by gravity. The rate 0%this flow to and from the washer 2 can be controlled by any suitablevalves, such as shown. at 20 and 21. In the receiving-tank water whichhas been used both for cooling and scrubbing the gas is min led with theammonia-absorbing agent,an therefore all well as to recover the 9 aportion of the or nearly all the ammpnia contained in the scrubbing andcooling wat r is recovered. By this means I recover eigh to ten percent. of ammonia in addition to that heretofore rccovered.

The water which is evaporated by the hot gas in the scrubber 2 passes assteam-vapor into the cooling-tower, where it is condensed and passesdown into the reservoir 13, and it is practically this water which formsthe excess that is returned from the tank 13 to the washer 2.considerable amount of moisture, which is condensed in its passagethrough the apparatus, so that an excess of.water is generally present,and consequently water need not be added. If necessary, however, fromtime to time additional water may be admitted at an convenient oint inthe system, preferably into the coo ing-water. 3

In the use of the apparatus described the gas from the producer passesin succession through the scrubber 2, the absorbin -tower 6, and thecooler 11, and thence out t rough the pipe 23 from the top of thecooling-tower. In its assage through the scrubber it is freed fiomd ofammonia is also absorbed by the scrubbing-water. It also evaporates a'ortion of this water. In its passage throng 1 the absorbing-tower itcomes in contact with the solution of sulfate of ammonia containing anexcess of sulfuric acid, which absorbs the Usually producer-gas containsa ust, soot, and tar, and a certain amount bulk of the ammonia remainingin the gas.

In its passage through the cooling-tower the most of the remainingtraces of ammonia is absorbed by the cooling-water and any moistureoriginally contained in the producers, along with the moisture and whichhas been added by the evaporation of water in the scrubber, is condensedand passes with the cooling-water into the receiving-tank 13. Thisexcess of water containing traces of ammonia, or a portion of it, isreturned by the pipe 16 to the scrubber. In the scrubber the water takeson more ammonia and thence passes,first, through the settling-tank 18-,and thence to the receiving-tank 9, where it is mingled with thecirculating liquor ofv the tower 6, which liquor contains an excess of.sulfuric acid, and hence absorbs the ammonia contained in the water,thus increasing the amount of ammonia in the liquor of theammonia-absorbing tower.

By means of the rocess described a considerable amount of ammonia isrecovered which. has heretofore been lost; also, the water evaporated inthe washer 2 and subse uently condensed in the cooler 11 is returned tothe washer along with any ammonia escaping from the absorbing tower 6.This water with its contained ammonia, as well as the ammonia absorbedin the washer, are delivereg to the ammonia-absorber 6 and recovereVarious forms and crra ments of eppe ratus other than those shox in thedrawings may he used for carrying out the process.

What I claiin is l 1. The process of recovering ammonia from coal orfoot gas, which consists in passing the gas through or in contact withwater to scruh the same, then passing the some through and in contactwith ainnionis ab gling said wet-er and liquor, wherehythc inn-m monis.in said Water is recovered.

3. The process of recovering ammonia from coal and fuel gases, whichconsists in passing the through or in contact with water in circulationto scrub the same, then subjecting the gas to un einmonia-shsorhingagent, 'sgein passing the gas through chin contact with Water incirculation to co'oi the" same, passing the excess of cooling-water tothe scrubber, and subjecting the excess of water trons the scrubber tothe action of an smmonia-ahsorhing agent.

4. The process of recovering ammonia from coal or fuel gases, whichconsists in passing the gas through or in contact with water incirculation to scruh the scene, then passing the some through or incontact with an mweenie-absorbing liquor, again passing the some throughor in contact with water to cool the some, and causing a portion ofWater from the cooler to flow to the scrubber, and a portion of thewater from the scrubber to how to anti he ningierl with theammoniaehsorhing liquor .5. The process of recovering 7 ammonia, fromcoal or fuel gas, which consists in passing the gas through or incontact with water to scrub the same, 'then passing the some through orin contiict'with an ifilllfifilfifi-Qb 'sorbing' liquor in circulation,again passing the so; no through or in contact with water in circulationto cool the same, thereby condensingthe moisture contained in the gasreturni 71g the excess of water from the cooler to the s sruhber, andcausing the excess of war ter from the scruhhcr to flow toend mingiewith the sinmount-absorbing liquor.

6. The process of cleaning gas which consists in gassing the gas throughor in contact with water 111 circulation to scrub the some, 7 thensullgec ing said gasto 2L cooling process and the? condensing themoisture contained therein, and returning the water of nonsense tion tothe scrubber.

7. The process of cleaning gas, which consis-ts in passing the gasthrough or in contact with water in circulation to scrub the same, endthen through or in contact with V1816! 1n circnlutiol to cool the some,thereby conlensing tile moisture contained in the gas, and returning theexcess of Water from the cooler to the scrubber.

8. The process of recovering ammonia from coal r. r fuel gases whichconsists in passing the gas through or in contact with water to scrubthe same, end then through and in contact with water containin sulfuricacid to absorb the ammonia therefrom, and conducting the excess of thescrubbing-Water to end mingling the some with the ammoniaabsorhing waterIn testiin any whereof I, the said EDWARD JAMES Dunn, have hereunto setmy hand.

EDWARD JAMES DUFF.

Witnesses r Runner 0. TOTTEN, J. R. KELLER.

